Its not at all obvious what your query is meant to be showing
The current one has multiple records for each part number
The query below gives one record per part number (758 in all) but whether its what you want I've no idea
Code:
SELECT tblPartMain.MfrPartNumber, tblSubAssemblyInfo.ChildID
FROM tblPartMain INNER JOIN tblSubAssemblyInfo ON tblPartMain.ID = tblSubAssemblyInfo.ComponentID;
Saved as Child Query-CR in the attached
If as I suspect, that's not correct, I suggest you give some examples of expected output